2 introductin mobile & cellular

A Brief Overview By

Engr. Abdul Razzaque MemonMCS (IT/MIS) ; B.E (Electronics) ; PE (PEC) ; B.A (Arts)

Web : http://www.uldhdqpia.webs.com

E mail : [email protected]

Transmitting voice and data using electromagnetic waves in open space

Electromagnetic waves Travel at speed of light (c = 3x108 m/s) Has a frequency (f) and wavelength ()

c = f x

Higher frequency means higher energy photons

The higher the energy photon the more penetrating is the radiation

by: Engr. Abdul Razzaque Memon


30MHz – 300MHz VHF300 MHz – 3GHz UHF3Ghz - 30GHz SHF> 30 GHz EHF

104 102 100 10-2 10-4 10-6 10-8 10-10 10-12 10-14 10-16

104 106 108 1010 1012 1014 1016 1018 1020 1022 1024

IR UV X-RaysCosmic

RaysRadio

Spectrum

1MHz ==100m100MHz ==1m 10GHz ==1cm

Microwave

Visible light

< 30 KHz VLF30Khz - 300KHz LF 300KHz – 3MHz MF3 MHz – 30MHz HF

• The information from sender to receiver is carrier over a well defined frequency band. This is called a channel

• Each channel has a fixed frequency bandwidth (in KHz) and Capacity (bit-rate)

• Different frequency bands (channels) can be used to transmit information in parallel and independently.



991 992 … 1023 1 2 … 799 991 992 … 1023 1 2 … 799

824-849 MHz 869-894 MHz

Reverse Channel Forward Channel

Channel Number Center Frequency (MHz)

Reverse Channel 1 <=N <= 799 991 <= N <= 1023

Forward Channel 1 <=N <= 799 991 <= N <= 1023

0.030N + 825.00.030(N-1023) + 825.0

0.030N + 870.00.030(N-1023) + 870.0

(Channels 800-990 are unused)

Channel bandwidth is 45 MHz

AMPS Phones: • frequency ~= 800 Mhz • wavelength ~= 37.5 cm

GSM Phones: • frequency ~= 900 Mhz • wavelength ~= 33 cm

PCS Phones• frequency ~= 1800 Mhz (1.8 Ghz)• wavelength ~= 16.6 cm

Bluetooth: • frequency ~= 2.4 Gz • wavelength ~= 12.5 cm


Assume a spectrum of 90KHz is allocated over a base frequency b for communication between stations A and B

Assume each channel occupies 30KHz. There are 3 channels Each channel is simplex (Transmission occurs in one

way) For full duplex communication:

Use two different channels (front and reverse channels)

Use time division in a channel


Channel 1 (b - b+30)

Channel 2 (b+30 - b+60)

Channel 3 (b+60 - b+90)

Station A Station B

Normally, on a channel, a station can transmit only in one way.

This is called simplex transmision To enable two-way communication

(called full-duplex communication) We can use Frequency Division Multiplexing We can use Time Division Multiplexing


FDD: Frequency Division Duplex


Base StationB

Mobile Terminal

M

Forward ChannelReverse Channel

Forward Channel and Reverse Channel use different frequency bands

TDD: Time Division Duplex


Base StationB

Mobile Terminal

M

A singe frequency channel is used. The channel is divided into time slots. Mobile station and base station transmits on the time slots alternately.

M B M B M B

Initially Internet and Telephone Networks is designed assuming the user terminals are static

No change of location during a call/connection A user terminals accesses the network always from a

fixed location Mobility and portability

• Portability means changing point of attachment to the network offline

• Mobility means changing point of attachment to the network online


Walking Users Low speed Small roaming area Usually uses high-bandwith/low-latency access

Vehicles High speeds Large roaming area Usually uses low-bandwidth/high-latency access Uses sophisticated terminal equipment (cell

phones)


Demand for Ubiquitous Computing• Anywhere, anytime computing and communication

You don’t have to go to the lab to check your email

• Pushing the computers more into background Focus on the task and life, not on the computer Use computers seamlessly to help you and to

make your life more easier.• Computers should be location aware

Adapt to the current location, discover services



Mobile Communications Network

BS MSC PSTN

PBX

Residence

Mobile Station(Phone)

LandLine

LandLine

Cell Site

Base stationsand other cell

sites

Two- to Three-Mile Radius

BS = Base StationMSC = Mobile Switching Center


Base Station(BS) Mobile Station

Base Station Controller

Mobility Database

Mobile Switching

Center(MSC)

Radio Network

Public SwitchedTelephone Network

• Mobile Station A station in the cellular radio service intended for

use while in motion at unspecified locations. They can be either hand-held personal units (portables) or installed on vehicles (mobiles)

• Base station A fixed station in a mobile radio system used for

radio communication with the mobile stations. Base stations are located at the center or edge of a coverage region. They consists of radio channels and transmitter and receiver antennas mounted on top of a tower.


◦ Mobile Switching Center◦ Switching center which coordinates the routing of

calls in a large service area. In a cellular radio system, the MSC connections the cellular base stations and the mobiles to the PSTN (telephone network). It is also called Mobile Telephone Switching Office (MTSO)

◦ Subscriber◦ A user who pays subscription charges for using a

mobile communication system

◦ Transceiver◦ A device capable of simultaneously transmitting

and receiving radio signals


• Control Channel Radio channel used for transmission of call setup,

call request, call initiation and other beacon and control purposes.

• Forward Channel Radio channel used for transmission of information

from the base station to the mobile

• Reverse Channel Radio channel used for transmission of information

from mobile to base station


• Simplex Systems Communication systems which provide only one-way

communication

• Half Duplex Systems Communication Systems which allow two-way

communication by using the same radio channel for both transmission and reception. At any given time, the user can either transmit or receive information.

• Full Duplex Systems Communication systems which allow simultaneous

two-way communication. Transmission and reception is typically on two different channels (FDD).


• Handoff The process of transferring a mobile station from

one channel or base station to an other.

• Roamer A mobile station which operates in a service area

(market) other than that from which service has been subscribed.

• Page A brief message which is broadcast over the entire

service area, usually in simulcast fashion by many base stations at the same time.



Cellular system / Network

Apart from the capacity limitation of these early systems, the other characteristic was that the carrier frequency was only re-used many tens or hundreds of kms away, so that no ‘co–channel’ interference would arise.

[co–channel = same frequency)


Cellular systems – cont. . .

Cellular systems are based on the concept of dividing the geographic service area into a number of cells and placing a low power transmitter in each of these, usually at the geographic centre.

The transmit frequencies are re-used across these cells and the system becomes interference rather than noise limited.


Mobile Cellular Telephone System

FrequencyA

FrequencyB

FrequencyC

FrequencyC

FrequencyF

FrequencyE

FrequencyA

FrequencyD

FrequencyA

FrequencyB

BaseStation

Tolloffice

Tolltrunk

Localloop

Landline

CentralOffice

Landline topublic

switchedtelephonenetwork

FrequencyG

FrequencyA

FrequencyF

FrequencyD

FrequencyE

FrequencyG

FrequencyB

FrequencyC

Masterswitching

center(MTSO)

Standard Type Year Intro

Multiple Access

Frequency Band(MHz)

Modulation Channel BW(KHz)

AMPS Cellular 1983 FDMA 824-894 FM 30

USDC Cellular 1991 TDMA 824-894 DQPSK 30

CDPD Cellular 1993 FH/Packet 824-894 GMSK 30

IS-95 Cellular/PCS 1993 CDMA 824-8941800-2000

QPSK/BPSK 1250

FLEX Paging 1993 Simplex Several 4-FSK 15

DCS-1900 (GSM)

PCS 1994 TDMA 1850-1990 GMSK 200

PACS Cordless/PCS

1994 TDMA/FDMA 1850-1990 DQPSK 300


Standard Type Year Intro

Multiple Access

Frequency Band(MHz)

Modulation Channel BW(KHz)

ETACS Cellular 1985 FDMA 900 FM 25

NMT-900 Cellular 1986 FDMA 890-960 FM 12.5

GSM Cellular/PCS 1990 TDMA 890-960 GMSK 200KHz

C-450 Cellular 1985 FDMA 450-465 FM 20-10

ERMES Paging 1993 FDMA4 Several 4-FSK 25

CT2 Cordless 1989 FDMA 864-868 GFSK 100

DECT Cordless 1993 TDMA 1880-1900 GFSK 1728

DCS-1800 Cordless/PCS

1993 TDMA 1710-1880 GMSK 200


First Generation (1G) Analog Systems Analog Modulation, mostly FM AMPS Voice Traffic FDMA/FDD multiple access

Second Generation (2G) Digital Systems Digital Modulation Voice Traffic TDMA/FDD and CDMA/FDD multiple access

2.5G Digital Systems Voice + Low-datarate Data

Third Generation (3G) Digital Voice + High-datarate Data Multimedia Transmission also


cdmaOne (IS-95)

GSM, DCS-1900 IS-54/IS-136PDC

Uplink Frequencies (MHz)

824-849 (Cellular)1850-1910 (US PCS)

890-915 MHz (Eurpe)1850-1910 (US PCS)

800 MHz, 1500 Mhz (Japan)1850-1910 (US PCS)

Downlink Frequencies

869-894 MHz (US Cellular)1930-1990 MHz (US PCS)

935-960 (Europa)1930-1990 (US PCS)

869-894 MHz (Cellular)1930-1990 (US PCS)800 MHz, 1500 MHz (Japan)

Deplexing FDD FDD FDD

Multiple Access CDMA TDMA TDMA

Modulation BPSK with Quadrature Spreading

GMSK with BT=0.3 DQPSK

Carrier Seperation 1.25 MHz 200 KHz 30 KHz (IS-136)(25 KHz PDC)

Channel Data Rate 1.2288 Mchips/sec 270.833 Kbps 48.6 Kbps (IS-136)42 Kbps (PDC)

Voice Channels per carrier

64 8 3

Speech Coding CELP at 13KbpsEVRC at 8Kbps

RPE-LTP at 13 Kbps VSELP at 7.95 Kbpsby: Engr. Abdul Razzaque Memon

2G is developed for voice communications

You can send data over 2G channels by using modem

Provides adat rates in the order of ~9.6 Kbps

Increased data rates are requires for internet application

This requires evolution towards new systems: 2.5 G


Evolution of TDMA Systems• HSCSD for 2.5G GSM

Up to 57.6 Kbps data-rate

• GPRS for GSM and IS-136 Up to 171.2 Kbps data-rate

• EDGE for 2.5G GSM and IS-136 Up to 384 Kbps data-rate

Evolution of CDMA Systems• IS-95B

Up to 64 Kbps


Goals• Voice and Data Transmission

Simultanous voice and data access• Multi-megabit Internet access

Interactive web sessions• Voice-activated calls• Multimedia Content

Live music


Evolution of Systems CDMA sysystem evaolved to CDMA2000

CDMA2000-1xRTT: Upto 307 Kbps CDMA2000-1xEV: CDMA2000-1xEVDO: upto 2.4 Mbps CDMA2000-1xEVDV: 144 Kbps datarate

GSM, IS-136 and PDC evolved to W-CDMA (Wideband CDMA) (also called UMTS)

Up to 2.048 Mbps data-rates Future systems 8Mbps Expected to be fully deployed by 2010-2015

New spectrum is allocated for these technologies



Western Eastern USA Europe Europe Emails 4.5 4.7 4.3 City maps/directions 4.3 4.2 4.2 Latest news 4.0 4.4 4.0 Authorize/enable payment 3.4 3.8 3.0 Banking/trading online 3.5 3.4 3.2 Downloading music 3.1 3.4 3.2 Shopping/reservation 3.0 3.1 2.9 Animated images 2.4 2.7 2.6 Chat rooms, forums 2.3 2.9 2.2 Interactive games 2.0 2.2 2.4 Games for money 1.8 1.8 1.8

(Means based upon a six-point interest scale, where 6 indicates high interest and 1 indicates low interest.)


IS-136PDC

GSMIS-95

IS-95B HSCSD

GPRS

EDGE

W-CDMAEDGE

TD-SCDMA

cdma200-1xRTT

cdma2000-1xEV,DV,DO

cdma200-3xRTT

2G

2.5G

3G

2nd Generation GSM -9.6 Kbps (data rate)

2.5 Generation HSCSD (High Speed ckt Switched data)

Data rate : 76.8 Kbps (9.6 x 8 kbps)GPRS (General Packet Radio service)

Data rate: 14.4 - 115.2 KbpsEDGE (Enhanced data rate for GSM Evolution)

Data rate: 547.2 Kbps (max) 3 Generation

WCDMA(Wideband CDMA)Data rate : 0.348 – 2.0 Mbps


Total Global Mobile Users: 860m

Total Analog Users: 71m Total US Mobile Users:

137.5m Total GSM Users: 669m Total TDMA Users: 84m Total European Users:

279m Global Montly SMSs/User:

36 SMS Sent in 2001: 102.9

billion

GSM Countries on Air: 171 #1 Mobile Country: China #1 GSM Country: China #1 SMS Country:

Phillipines #1 Cell Phone Vendor:

Nokia #1 Network in Europa: T-

Mobil #1 Network in Japan:

DoCoMo #1 Telecom Infrastructure

Company: Ericsson


2 introductin mobile & cellular

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